CORRECTION: Aspirin may help older colon cancer patients live longer

NEW YORK (Reuters Health) - Older adults with colon cancer who were prescribed a daily aspirin were less likely to die than those who weren't, according to a new study.

While the results need to be confirmed with more rigorous studies, they add to the evidence linking aspirin use to longer survival for cancer patients. Studies have also suggested the inexpensive drug can prevent some types of the disease from occurring in the first place.

Medical guidelines currently endorse the use of low-dose aspirin to prevent heart disease, but not to fight or prevent cancer.

The new study, published in the Journal of the American Geriatrics Society, included more than 500 colon-cancer patients in the Netherlands aged 70 and older. More than 100 were prescribed daily low-dose "baby" aspirin for heart protection after their cancer diagnosis.

Between 1998 and 2007, the death rate for those prescribed aspirin was about half that of the non-aspirin users. The effect was biggest in people with more advanced cancer and in those who received no chemotherapy.

Anything that might improve survival in elderly adults with colon cancer would be welcome, since there is no consensus on whether to use chemotherapy in those patients, according to the study.

Previous studies have also associated aspirin use with increased survival. Research published in October in the New England Journal of Medicine suggested that aspirin therapy could extend survival for colon cancer patients whose tumors had a specific genetic mutation.

Still, more scientifically rigorous randomized controlled trials will be needed to confirm the findings of studies that are based on observation after the fact, and therefore less definitive about what actually causes the effect seen.

"We're pretty sure this is a real effect, but we're not sure of the magnitude," said Dr. Gerrit Jan Liefers of Leiden University Medical Center in the Netherlands, an author of the new study. He said he didn't expect randomized trials would show such a large survival advantage. Liefers is working to develop such a trial in the Netherlands.

One limitation of the study is that it looked at aspirin prescriptions, not actual use of the drug. (Low-dose aspirin for heart-disease protection isn't available over the counter in the Netherlands.) It's possible that heart benefits from aspirin might have helped the patients live longer, but the study authors said that alone couldn't account for the big difference in death rates. Also, there might be differences between the groups unaccounted for by researchers that led to the improved survival among the aspirin users.

Liefers said it's not completely clear how aspirin might combat colon cancer. One likely route: blocking the enzyme cyclooxygenase-2, or COX-2, which is involved in inflammation and is expressed in about 70 percent of colon tumors.

Boris Pasche, director of the hematology and oncology division at the University of Alabama at Birmingham, said it would be helpful to figure out who would benefit from and who could skip daily aspirin.

"It's a fairly benign drug, but it has side effects," including bleeding in the gastrointestinal tract and the brain, Pasche said.

He said patients should discuss with their physicians whether it makes sense to take aspirin at this point. "This supports the concept, but we need a prospective randomized trial," he said.